1. Field of the Invention
The present invention relates to a tape member or a sheet member to be used for electromagnetic coils, electromagnetic appliances, or the like and a method of producing a tape member or a sheet member.
2. Description of the Related Art
Electromagnetic appliances can be made highly efficient, compact, and economical by improving a cooling property of an electromagnetic coil. As a method of improving the cooling property of an electromagnetic coil, it is desired for an electric insulation material that is to be used in the periphery of the electromagnetic coil to be highly thermally conductive. So far, a highly heat conductive mica-based sheet-like body having a lining material containing inorganic powder has been disclosed (reference to Patent Document 1). However, according to this method, since the mica layer does not show sufficient heat conduction, the heat conductivity of an insulating layer is insufficient in the case of production of an electromagnetic coil.
Also, a method of improving the heat conductivity of a resin by using a crystalline epoxy resin as the resin is published (reference to Patent Document 2). However, the resin is difficult to handle because it is solid at a normal temperature.
Further, a method of using a scaly and highly heat conductive material and mica is published (reference to Patent Document 3). However, in this method, unless the scaly and highly heat conductive material has a sufficiently high aspect ratio, mica paper cannot be produced and, although scaly alumina is employed as an example of a material having a high aspect ratio, which is the ratio of the diameter and the thickness, alumina has a high dielectric constant and thus is not preferable for an electric insulation material.
Patent Document 1: Jpn. Pat. Appln. KOKAI Publication No. 2002-93257
Patent Document 2: Jpn. Pat. Appln. KOKAI Publication No. 11-323162
Patent Document 3: Jpn. Pat. Appln. KOKAI Publication No. 2000-58314